A developer unit such as a binary ink developer (BID) unit is a consumable that is often used in a printing apparatus such as a liquid electrophotographic (LEP) printing apparatus. This consumable is generally made from custom and/or off-the-shelf components. In LEP printing apparatus, generally a photosensitive drum is charged and is then selectively exposed to a laser to form a charge pattern that corresponds to an image. The drum is then contacted with a BID unit that selectively transfers a liquid ink pattern to the charge pattern. The liquid ink pattern is transferred from the photosensitive drum to a print medium, for example, through an intermediate member, to form the image on the print medium.